The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Philippines typhoon damage unclear

The extent of destruction caused by powerful Typhoon Hagupit, which is battering the Philippines, remains unclear, an Australian aid worker says.

Oxfam's Philippines country director Justin Morgan said Typhoon Hagupit was moving across the area very slowly, meaning the heavy rain and strong winds it's been bringing remain in the same locations for long periods of time.

He told AAP on Sunday that it was difficult for communications to reach some of the more remote areas of the island nation, which is still recovering from last year's devastating Typhoon Haiyan.

But he said the government had advised there had been no loss of life, unlike last year when 7350 perished.

"Our teams have been out this morning and are working with the government to help with the first stage of the response, which is making sure people have access to water and sanitation," he said.

"We know there has been some level of damage to some of the transitional shelters that had been built in response to Typhoon Haiyan, however, we think we will be able to get back to the stage we were at before quite quickly."

Aid workers from World Vision are also on the scene and reported fallen trees and roofs blown off by the storm.